Recently, much interest has been directed towards the diesel engine due to its efficiency, durability and economical aspects. However, diesel emissions have been scrutinized both in the United States and Europe. As such, stricter environmental regulations will require diesel engines to be held to relatively stringent emission standards. In the near future, regulations will require NOx treatment in combination with particulate filtering. This will lead to the need to develop very complex exhaust systems including NOx catalyst integration into DPF (such as SCR or LNT catalyst) to decrease exhaust system treatment volume, i.e., decrease the number of after treatment components.
One of the biggest challenges in integrating this additional catalyst exhaust treatment is minimizing the resulting backpressure which can penalize and diminish engine performance. Generally, it has been accepted that smaller honeycomb wall thickness and higher frontal areas enable a lower pressure drop across a washcoated particulate filter. However, the significantly high level of washcoat loadings that can be required to meet strict regulations can result in significant increases in backpressure, thus resulting in diminished engine performance. Accordingly, there is a need in the art for honeycomb filters that can enable the application of high levels of washcoat loadings while minimizing the undesired increase in backpressure.
The present disclosure provides a greater understanding of the relationship between honeycomb cell geometry and washcoat thickness and provides methods for optimizing cell geometries that can enable high washcoat loadings while minimizing relative increases in backpressure.